Electron tube coder device



July 2l, 1953 J. A. vlLLE ET AL ELECTRON TUBE coDER DEVICE Filed July 9, 1949 Patented July 21, 1953 UNITED 'ST and ierre Alphonse Herreng,

Montrouge,

France, assignors to Societe Alsacienne de Constructions Mecaniques, a -corporationof vFrance Application July .9, 1949, Serial No. 103,904 In France July 21, 1948 This invention relates to systems "for transmitting complex intelligence Waves in vwhich the instantaneous amplitudes of said'waves are analyzed vat recurrent time intervals and the amplitude samples thus obtained are translatedrinto coded signals consisting of groups of 'an integer number n of pulses, each pulse of which can assume one or the other of two values `or possible signalling conditions. It relates more particularly to coder and decoder devices comprising essentially electronic 'tubes containing means for generating an electron beam, means for deflecting said electron beam, an electron collecting anode land a mask or apertured electrode with cut out parts inserted on the path of the beam. In the same way as other and previously known coder systems, theperiormance of thehereunder described coder deviceis essentially based on the fact that aiter the above mentioned sampling and previous to its [being translated into code signals,

the complex intelligence wave to be transmitted is rst transformed into an electric voltage, hereinafter called the modified signal voltage, having a square wave-shape whose peaks have amplitudes related to the sampled amplitudes, being, for instance, proportional to the latter. It is further known that, in practice an exact proportionality is unnecessary. 1f the sample amplitudes vary between extreme values respectively proportional to integer knumbers l and 2, it -is generally deemed suiicient to give the modied signal voltage one of a series of 2ndistinct values and to substitute for the exact proportional value corresponding to the sampled amplitude the nearest approximation to it, by excess or defect, in

the series just mentioned. Devices for obtaining such a modified signal voltage from `an intelligence wave are wellknown in I'the art.

Transmitting systems are known, essentially comprising coding devices made up Yof electronic tubes wherein the electronic beam is deiiected in a rst direction, by an amount depending on the amplitude of each sample, then deflected in ya second direction to scan the mask and generate inthe anode circuit groups ofpulses, each one of .which corresponds to athepassing of the beam through one'of the cutout portions Aof .the mask. In-such tubesthe mask 'should comprise as many groups of-solid or Vcut-out portions, usually in a two dimensional array'as there are distinct sampled amplitudes. The two-dimensional scanning of -a predetermined Igroup by the 'beam raises difficulties. According to one of the main-characteristics of "the invention, the vtransmitting device comprises 'essentially Aa tube of `simpler y3 Claims. (01.332-111 construction wherein the combinations :of pulse groups :are generated `by :displacement and 'scanning in onedirection'only, the 'mask lcomprising a single row of cutout portions.

The vinvention is 'based "on the fact that it is possible to classify all the 2n possible Ygroups of 1L pulses, e'ach of which may vassume 'either 'one of two values and representing 'the 2'" amplitudes distinguished duringthe sampling of a'complex wave into such an order that `th`e (vz-1') :last pulses of 'a group "have individu-ally Tthe 'same values as the (1k-1) "firstpulsesofth'efollowing group. f

4For instance, in the 'casewh'ere'1t=4,accord ing to a well'known convention, i'f"ithetwo "p'ossible values of each pulse are represented 'by-the gures 0 and '1, the .16"po's'sible groups may "be arranged as follows: 'y 1111 1110 1101 1011 .01.10 `1100 1001v 0010 0101 1010 0100 1000 .0000, 0001 0011 01,11

By Writing the same'combinations'successively yand having them overlapso as'to lhave rthe'three last iigures'of one combinationidentical with'the three iirst iigures of the following combination, one obtains:

According to one feature of vthe invention, at the sending end of a transmission systemA lthe coder device comprises essentially a tube containing means for generating an electronic beam, means for deflecting said beam in one direction, an electron 'collecting anode and a mask interposed on the beam trajectory and comprising a row of vsolid or cutout elements, said cut 'out portions beingarranged in such -amanner 'that when the 'maskis scanned by thebe'am, Ithe-27L possible combinationsof solid or'cut out elements are met Aonly once, taking the 'Kn-'1) 'last .elements of leach combination as the Av n'l) Lrst elements'of the following combination.

For instance, kin the case lwhere1t=el,already considered above, the solid and cutout elements of the mask-may correspondvrespectively to the 'iection the-scanning, in--recurrence withea'ch 3 modified signal voltage of a number of solid or cut out elements of the mask equal to the number of pulses in the coded groups, and means for collecting the pulses generated in the circuit of the anode of the tube by the passing of the beam through the cut out portions of the mask.

The invention will now be more particularly described with reference to the accompanying drawings illustrating the application of the method according to the invention to la multiple telephone transmission device. In the drawings,

Figure 1 illustrates, schematically, a coder electron tube which constitutes the essential element of the device;

Figure 2 illustrates, in front view and on a larger scale, one of the electrodes of the above tube;

Figure 3 illustrates a block diagram of the main elements of a two channel transmitting device constructed in accordance with the invention;

Figure 4 is a diagram representing the wave shape of the voltages applied to certain electrodes of the coder tube of a transmission channel as well as the shape of the code signals generated by this tube.

In the example shown, the amplitude of the signal in each channel is sampled with a recurrent frequency F and the amplitude value is finally transmitted in the form of a conventional signal constituted by n pulses. The sampling times in the various channels are offset with respect to one another so as to ensure, in each cycle of frequency F the successive transmission of a code signal group for each one of the N channels associated in the multiple transmission. The possible range of variation of the signal amplitude is divided into 27L elementary intervals provided with a rank number.

In order to simplify the description now given of a practical application of the invention, it will be described as applied to a transmission assembly having two channels (i. e. N:2) and making use of code signal group constituted by four pulses, (i. e. n:4).

The coder tube I, illustrated in Figure l, which is an electron tube according to the invention, comprises an electron emitting cathode 2, an electrode 3 controlling the intensity of the electron beam and operable to suppress the same, a focussing electrode 4, vertical deflection plates 5, an electrode B consisting of a mask provided with windows and a collecting anode l.

The mask electrode 6, disposed along the deflection part of the electron beam shown in front elevation in Figure 2 comprises a plurality of narrow horizontal windows 8, whose distribution along the major axis of the electrode corresponds to that of the figures in the basic sequence, hereinbefore referred to, there being one window corresponding to each figure 1 of said sequence, and the various solid parts or windows individually representing gures in said sequence having equal or nearly lengths along said major axis. The corresponding rank for the 16 Igures of the sequence has been indicated opposite the cor responding intervals on the screen 6.

The Various electrodes of the tube l are energized in accordance with the conventional technique, by voltages ensuring their normal operation. The control electrode and the deflection plates are subjected respectively, to voltages which, (a) start the beam only at certain in stants and (b), vary the point of impact Of the beam on the mask electrode as will be hereinafter explained.

In the block diagram illustrated in Figure 3, 3i represents a basic generator supplying the frequency F. 32 andr 32' represent the two coder tubes of the two associated channels. The code signals generated, alternately, by these tubes are applied by line 33 to the transmission circuit. te and 34 are two square wave voltage generators each controlled by the basic generator and each actuating the beam intensity control electrode of its associated tube so as to cause an alternate starting of the beams of the two tubes; 35 and S5 are two saw tooth voltage generators controlled by the basic generator 3! and actuating, in alternation, the defiection plates of the two tubes. 3S and 35' are two square wave voltage generators also controlled by generator 3l, actuating, in alternation, the deflection plates oi the two tubes. These square wave voltages are respectively amplitude modulated from the signal voltages in each channel, which are supplied by lines 37, 3'1", and constitute what'has been hereabove called the modified signal voltage to the instantaneous amplitude of the signal at one sampling instant.

The operation of the above elements will be better understood by referring to Figure 4, where the times and signal amplitudes have been represented on two axes of 13o-ordinates. The figure refers to the rst one of the two associated channels.

The curve 4| shows, on an arbitrary scale, the amplitude of the signal of the rst channel as a function of time. The time interval i3-44 is allotted to the transmission of a signal from the first channel, 3-A5 to a signal from the second channel, l5-G6, again to a signal from the first channel and so on. The time interval @1t-4E is the reciprocal of the sampling frequency Each interval such as i3-lit is divided into four elementary intervals, each of them allotted to the sending of a pulse of the four element code signal group.

The saw tooth curve 41 shows the voltage provided by the generator 35 and applied to the deection plates of the electron tube.

As a square wave voltage, in phase with the said saw tooth voltage, is applied by the generator 34 to the intensity control electrode of the elecm tron tube, the beam is on only during the time intervals 43-4, 45-46, etc.

The straight line segments 4t represent the resultant voltage applied to the deection plates at the times when the beam is on, which voltage is the sum of the saw tooth voltage Lil and the amplitude modulated square wave voltage or modified signal voltage 43. The heig t (that is to say the position intermediate the ends of the screen electrode), of the impact point of the beam on the mask electrode is proportional to this voltage. The correspondence between the window locations on the mask electrode and the voltages applied to the deflection electrodes has been shown on a Vertical axis at the right hand side of the figure.

It will be seen that the amplitude of the square wave voltage 43 has been adjusted in such .a manner that the beam impact sweeps l5 inter-` vals of the screen when the signal voltage passes from its minimum to its maximum value and that the amplitude of the saw tooth voltage 49 has been adjusted so as to cause a deection of four intervals.

At the instant 43, at which the amplitude of 4| has been sampled, the deection voltage is raised agneau-4s 5 to .Q52 and then fcomestback, .1inearly,to the ;level 57i. sloperof theisaw ito'othwavezis adjusted in such a manner #that Athis part of tit :is gone through 'duringzthe .timetinterval A15-'411. .During fthis time, :the beam :sweeps through four intervals of/.the mask and thetub'e lpasses afshort pulse every time the beam goes through a window. The pulses thusfgenerated:constitute the code group characterizing the .amplitude of 4|. This:groupfcomprisingfinthe-.example shown one pulse 'during the second and 4third elementary intervals, is,shown .at 53.

A similar process is eifectedduring the'time interval G`5-46. 'Thecode groupgenerated comprises `only one pulse during athis last interval.

.It willfbesnotedthatthe pulsesithus generated can be;shifted relatively.totimerdue to 'fthe -fact that .the amplitude .of .the `'signal -does ,not .igen- ,erally correspond .to .a whole .number of =ele mentary :amplitude .intervalsdiy a duration .smaller than Ythat `of .the elementary finterval. .The signal combinationishowever, formed ,withoutsany uncertainty, .providedthemask=.el'ectrode windows are narrow enough.

The code signals of .the second channel 'are generated in the .same manner, ithe only .difference being that theA signalszmustbe generated in alternance with those Aof .therstchanneL- The operating time shift Aof .the elements in the two channels Iis .obtained easily 'sinceall the 4elements of ithesisignal generatingrcircuitsare controlled by the same basic generator.

It is evident that the invention applies to a transmission system having any number of channels, the electron tubes being merely `actuated alternately as a polyphase system.V

The present invention also -applies to systems of secret transmission in which the signals must be impossible to decipher without the knowledge of a secret code.

In accordance with the method of the invention described-above, the correspondence between the amplitude value of a signal to be transmitted and the corresponding code signals is effected through a sequence of 2n binary digits, which ensures a relative secret. 'I'he secret nature of this transmission may be made practically absolute by varying, in time, the rank from which are counted, in the basic sequence, the combinations of n digits and consequently the correspondence between the amplitude values and the code signals.

These variations can be effected in a practically instantaneous manner and synchronously at the two ends of the communication link. The instants and amplitudes of these variations may be the objects of a secret code known only to the authorities responsible for the transmission,

The embodiment of the invention described -above by way of example, concerns a multiple telephone transmission system.A It will be realized that the invention is also applicable to any telecommunication system, simple or multiple, wherein a succession of messages must be transmitted in the shape of code signals.

What we claim is:

1. An electron tube for use in a coder for translating an intelligence wave represented by a variable electric voltage occurring at recurring time intervals into groups of code signals, each group comprising an integer number n of pulses, each pulse being of one or the other of two possible signalling conditions; said electron tube comprising a cathode emitting electrons, an electron gun for the production of an electronic beam, a control. .felectrodeor establishing or interrupting said zbeam, Ydefle'cting electrodes for deflecting said vbeamr in a given :direction under thefaction ofan external voltage, fanapertured electrode disposed in the tlpath of .said beam Sand having a-'singlerow -ofrsolicl'and cut out portions extending valong said given direction and numberingi21}-.Cn-:1)sg2 said solid ann-'cut outiportions being-'arrangedin such anorder thateach group of fn consecutive solid Vand cut out portions is different from any `other such group, iand an anode 'for' collecting-the electrons `of 'said beam which fpass *through fthe kcut .out portions of isaid apertured electrode.v

'2. In fa 'communication 'system in which the amplitude of `an :intelligence wave is 'sampled 'at recurring time lintervalsandfeach sampled amplitude'is-'thereafter represented `by a group-otra xedinteger numbern of "permutation code signals which are of one or the other of two dilerent possible signallingconditions; 'an electronic -device for converting said intelligence wave into cod'esignals,comprising an v'electronic tube including a cathode emitting electrons, an electron gun Ifor the production of Van electronicbeam, 'a control electrode for establishing or interrupting said beam; deflecting electrodes for deflecting said Ybeam'ina .given vdirection under the action of an external voltage, Yan apertured electrode disposedin'the'p-atho saidbeam'and having a single row'of solidfand out .out'por'tions extending along said given direction and numbering 2"-l-(n-1), said solid and cut out portions being arranged in such an order that each group of n consecutive solid and cut out portions is different from any other group of n consecutive portions,

and an anode for collecting the electrons of said beam which pass through the cut out portions of said apertured electrode, an external circuit connected to said anode, means eiiective during each sampling of the intelligence wave to be converted into code signals for applying to the said deflecting electrodes a voltage approximately proportional to the sample amplitude of said intelligence wave thereby directing said electron beam at a related predetermined part of said apertured electrode, means for applying to said control electrode a controlling voltage so as to establish said electron beam only during predeterminer recurring time intervals, means Vfor applying to said deilecting electrodes and during said recurring time intervals a sweeping voltage so as to cause said electron beam to sweep said predetermined part of said mask apertured electrode along said given direction and over a dis tance encompassing n consecutive portions of said apertured electrode, thereby causing a sequence of pulses to be produced in said external circuit, and means for impressing said pulses upon a working circuit.

3. In a communication system using coded signals, and including at least one communication channel in each one of which the amplitude of an intelligence wave is sampledA at recurrent time intervals and wherein each sampled amplitude is thereafter represented by a group of 11, permutatable pulses, each pulse being of one or the other of two possible signalling conditions; a transmitting device comprising a main generator of electric oscillations having a basic frequency corresponding to the recurrenttime intervals for sampling of the amplitude of said intelligence wave, at least one electronic tube, each said electronic tube including a cathode emitting electrons, an electron gun for the production of an 7 electronic beam, a control electrode'for establishing or interrupting said beam, deflecting electrodes for deecting said beam ina given direction under the action of an external voltage, an apertured electrodedisposed in the path of said beam and having a single row of solid and cut out portions extending along said given ,direction and numbering 2"-i-(n-1), said solid and cut out portions being arranged in such an order that each group of n consecutive solid and cut out portions is different from any other group of n consecutive solid and cut out portions, and an anode for collecting the electrons of said beam which pass through said cut out portions of the apertured electrode, a generator of square waveshaped electric voltage having its frequency and phase controlled by the said main generator, means for controlling the amplitude of said square Wave-shaped Voltage proportionally to the sample amplitude of the intelligence Wave to be transmitted, means for applying said square wave-shaped Voltage to the defiecting electrodes of each said electronic tube thereby directing said beam at a predetermined related part of said apertured electrode, a generator of sawtooth electric voltage of a predetermined amplitude having its frequency and phasecontrolled by the said main generator, means for applying said saw-tooth voltage to the deflecting electrodes of each said electronic tube simultaneously with said square Wave-shaped voltage to cause said 8 beam to sweep said related part of the apertured electrode of a distance encompassing n consecutive portions of said lapertured electrode, an external circuit collecting the current from the anode of each said tube, and means for impressing said current upon a working circuit.

JEAN ANDR VILLE. ANDR PAUL PAGES. Y Y PIERRE ALPHONSE HERRENG. vReferences cited in the fue ofthis patent UNITED STATES PATENTS Number Name l Date 1,757,345 Strobel May 6, 1930 2,144,337 Koch v Jan. 17, 1939 2,189,898- Hartley Feb. 13, 1940 2,437,707 Pierce Mar. 16, 1948 2,441,296 Snyder May V1-1, 1948 2,438,908 Goodall Apr. 6, 1948 2,451,044 Pierce Oct. 12, 1943 2,453,461 Schelleng Nov. 9, 1948 2,458,652 .Sears Jan. 1l, 1949 2,463,535 Hecht Mar. 8, 1949 2,473,691 Meacham June 21, 1949 2,485,821 Gloess et al 0013.25, 1949 2,489,883 Hecht f Nov. 29, 1949 2,496,633 Llewellyn Feb. 7, 1950 2,505,029 Corbrey Apr. 25, 1950 2,537,843 Mecham Jan. 9, 1951 

